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A127071
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Quotients (3^p - 2^p - 1)/p, where p = prime(n).
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9
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2, 6, 42, 294, 15918, 122010, 7588770, 61144062, 4092816966, 2366546223930, 19924878993558, 12169831579784970, 889585223857256850, 7633882758103350126, 565719451451489679414, 365721616201373974378410
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OFFSET
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1,1
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COMMENTS
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Prime p divides 3^p - 2^p - 1. 42 = 2*3*7 divides a(n) for n>2.
Numbers n such that n divides 3^n - 2^n - 1 are listed in A127072.
Pseudoprimes in A127072 include all powers of primes {2,3,7} and some composite numbers that are listed in A127073.
Numbers n such that n^2 divides 3^n - 2^n - 1 are listed in A127074.
Numbers n such that n^3 divides 3^n - 2^n - 1 are {1,4,7,...}.
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LINKS
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FORMULA
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a(n) = (3^prime(n) - 2^prime(n) - 1)/prime(n).
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MAPLE
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seq((3^ithprime(n) -2^ithprime(n) -1)/(ithprime(n)), n=1..20); # G. C. Greubel, Aug 11 2019
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MATHEMATICA
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Table[(3^Prime[n]-2^Prime[n]-1)/Prime[n], {n, 1, 20}]
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PROG
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(PARI) vector(20, n, p=prime; (3^p(n) - 2^p(n) -1)/p(n) ) \\ G. C. Greubel, Aug 11 2019
(Magma) p:=NthPrime; [(3^p(n) -2^p(n) -1)/p(n): n in [1..20]]; // G. C. Greubel, Aug 11 2019
(Sage) p=nth_prime; [(3^p(n) -2^p(n) -1)/p(n) for n in (1..20)] # G. C. Greubel, Aug 11 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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